...I was hosting a playgroup yesterday and asked my friend, Shannon, how her lilacs were coming along. Last year (maybe 2 years ago now) she dug up some of the "suckers" from my lilac bush and transplanted them into her own yard. She simply dug up a couple of them (with their roots, of course) and stuck them in her yard where she wanted them. She didn't treat the roots or do any special soil preparation. They are coming along fine. She says she's done this before. Good luck. It doesn't hurt to try.
-Karen